Williamsport weather in December

In December, Williamsport sees average daytime highs of 38°F and overnight lows near 26°F, with 3.5 in of precipitation across 10.1 wet days and about 9.1 hours of daylight. It is the 10th-warmest and 9th-wettest month of the year here.

Highs ease over the month, from about 41°F in the first days to 36°F by the end. The sky is clear or mostly clear about 15% of the time in December, and the air most often feels dry.

Daylight stretches from about 9 h 12 min at the start of December to 9 h 06 min by month's end. Set against the rest of the year, December is Williamsport's 12th-clearest and 5th-windiest month. For the whole year in context, see Williamsport's year-round climate.

Daytime high
38°
10th warmest
Overnight low
26°
3rd coldest
Precipitation
3.5 in
10.1 wet days
Daylight
9 hours
7:33 AM – 4:35 PM
Cloud cover
73%
12th clearest
Wind
6 mph
5th windiest
Solar energy
1.56 kWh/m²
Travel score
0.0
out of 10

Williamsport is city in and county seat of Lycoming County, Pennsylvania, United States.

Density
1,196/km²
people per km²
Founded
1769

Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.

Temperature in December

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 41°F in the first days to 36°F by the end.

A typical December day in Williamsport reaches about 38°F in the afternoon and slips back to 26°F overnight — a 12°F spread between the day's warmth and the night's chill. On most days the high lands between 27°F and 49°F. Set against its neighbours, December runs about 10°F cooler than November and about 5°F warmer than January.

20°40°60°151015202531
Avg high (°F)Avg low (°F)
14230
24229
34129
44129
54128
64028
74028
83927
93927
103927
113826
123826
133826
143826
153825
163725
173725
183725
193725
203724
213724
223724
233624
243624
253624
263624
273623
283623
293623
303523
313523

How December really feels in Williamsport

Once humidity and wind are folded in, December averages 0 days that feel above 90°F and 31 that feel at or below 32°F — the comfort signal a plain temperature reading hides.

Days feeling ≥ 90°F
0
heat index over the day's high
Days feeling ≤ 32°F
31
wind chill below the day's low

The story in December is cold — wind chill drags the overnight "feels like" below the raw low.

Williamsport weather by month

How December compares with the rest of the year at a glance. December is the 10th-warmest and 9th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan33° / 20°3.210.16.39.40.0
Feb36° / 21°2.79.15.610.30.0
Mar46° / 29°3.9114.411.71.1
Apr58° / 40°4.111.81.213.14.1
May68° / 49°4.013.2014.35.8
Jun77° / 58°4.211.9014.96.4
Jul81° / 63°3.711.5014.76.2
Aug80° / 62°3.710.5013.76.5
Sep72° / 54°4.69.5012.36.8
Oct60° / 43°3.9100.310.94.9
Nov48° / 34°3.591.49.71.8
Dec38° / 26°3.510.14.69.10.0

Cloud cover in December

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 15% of the time in December, the cloudiest month of the year.

Beyond those clear spells, partly cloudy skies cover about 13% of December, with mostly cloudy or overcast conditions the remaining 72%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
12872
22872
32872
42872
52872
62773
72773
82773
92773
102773
112872
122872
132872
142872
152872
162872
172872
182872
192872
202872
212971
222971
232971
242971
252971
262971
273070
283070
293070
302872
312872

Chance of precipitation in December

Any precipitationSnow

Williamsport gets around 3.5 in of rain and snow over 10.1 wet days in December. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable precipitation averages around 33% and peaks near 34% on the wettest days, and about 5 days bring snow.

0%10%20%30%40%151015202531
Rain chance (%)Snow chance (%)
13310
23311
33312
43312
53313
63314
73415
83415
93416
103417
113417
123417
133417
143417
153417
163317
173316
183316
193315
203215
213214
223114
233114
243113
253113
263113
273113
283113
293113
303114
313214

Humidity in December

DryComfortableHumidMuggyOppressiveMiserable

Most of December feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.

By dew point, December lands in the dry band about 100% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202531
Dry (%)
1100
2100
3100
4100
5100
6100
7100
8100
9100
10100
11100
12100
13100
14100
15100
16100
17100
18100
19100
20100
21100
22100
23100
24100
25100
26100
27100
28100
29100
30100
31100

Wind in December

Winds average 6 mph in December.

Across December, daily wind ranges from about 6 mph on the calmest days to 7 mph at its breeziest. It stays fairly steady from day to day.

0246810151015202531
Wind speed (mph)Feels
16calm
26calm
36calm
46calm
56calm
66calm
76calm
86calm
96calm
106calm
116calm
126calm
136calm
146calm
156calm
166calm
176calm
186calm
196calm
207calm
217calm
227calm
237calm
247calm
257calm
267calm
277calm
287calm
297calm
307calm
317calm

Sunrise & sunset in December

DaylightNight

Daylight runs from about 9 h 12 min at the start of December to 9 h 06 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 6 minutes over December. Sunrise moves from 7:20 AM to 7:39 AM, and sunset from 4:35 PM to 4:43 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
19.27:204:35
29.27:214:35
39.27:224:35
49.27:234:35
59.27:244:34
69.27:254:34
79.17:264:34
89.17:274:34
99.17:284:34
109.17:294:34
119.17:294:34
129.17:304:35
139.17:314:35
149.17:324:35
159.07:324:35
169.07:334:35
179.07:344:36
189.07:344:36
199.07:354:36
209.07:354:37
219.07:364:37
229.07:364:38
239.07:374:38
249.07:374:39
259.07:384:39
269.07:384:40
279.07:384:40
289.07:394:41
299.07:394:42
309.17:394:42
319.17:394:43

Solar energy in December

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in December, about 1.56 kWh/m² — the year's lowest.

For context, solar energy here swings from a low near 1.56 kWh/m² to a high of 5.98 kWh/m² in June across the year — December's 1.56 kWh/m² sits near the bottom.

00.511.522.5151015202531
Solar energy (kWh/m²)Level
11.6Dim
21.6Dim
31.6Dim
41.6Dim
51.6Dim
61.6Dim
71.6Dim
81.6Dim
91.6Dim
101.6Dim
111.5Dim
121.5Dim
131.5Dim
141.5Dim
151.5Dim
161.5Dim
171.5Dim
181.5Dim
191.5Dim
201.5Dim
211.6Dim
221.6Dim
231.6Dim
241.6Dim
251.6Dim
261.6Dim
271.6Dim
281.6Dim
291.6Dim
301.6Dim
311.6Dim
Planning a trip in December

Is December a good time to visit Williamsport?

Our two travel scores rate December for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).

0.0
Sightseeing
10th-best month of the year
0.0
Beach & pool
9th-best month of the year

December is a weaker month for outdoor sightseeing in Williamsport.

What to pack for Williamsport in December

From December's temperature range, rain chance, sun and wind — what's worth putting in the bag.

In December, Williamsport sees daytime highs around 38°F and nights near 26°F. Pack a warm layer and a heavy coat. Worth having: rain gear. About 10 days see rain.

a warm layera heavy coatrain gear

UV index in Williamsport in December

LowModerateHighVery highExtreme

Clear-sky midday UV in December peaks around 1. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Williamsport peaks around June 23 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 21 at about 1 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 8 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighVery highHighModerateLowJun 23UV 9Dec 21UV 1
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar5Moderate
Apr6High
May8Very high
Jun9Very high
Jul9Very high
Aug6High
Sep6High
Oct3Moderate
Nov2Moderate
Dec1Low

Air quality in Williamsport in December

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where December falls, not just the annual average.

Air quality in Williamsport is worst in July — around 15 µg/m³ PM2.5 (moderate), about 2.4× the cleanest month (November, 7 µg/m³).

Modeled monthly averages (CAMS reanalysis, 2015–2024).

01020JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodJul 1415 µg/m³Nov 127 µg/m³
PM2.5 (µg/m³)Level
Jan9Good
Feb10Good
Mar11Good
Apr11Good
May13Moderate
Jun14Moderate
Jul15Moderate
Aug13Moderate
Sep11Good
Oct7Good
Nov7Good
Dec8Good
Location & terrain

Where is Williamsport?

Williamsport sits at 41.2°N, 77.0°W, 518 ft above sea level, in United States. The nearest listed city is Back Mountain, 53 mi away.

Topography around Williamsport

How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Williamsport.

Within 2 miles, the terrain around Williamsport has significant variations in elevation — a maximum elevation change of 1,148 ft around an average of 686 ft above sea level; within 10 miles, significant variations in elevation — a maximum elevation change of 1,585 ft; within 50 miles, large variations in elevation — a maximum elevation change of 2,228 ft.

The land around Williamsport is covered by trees (48%) and artificial surfaces (29%) within 2 miles, trees (68%) within 10 miles, and trees (79%) within 50 miles.

2 miles
1,148 ft
10 miles
1,585 ft
50 miles
2,228 ft
treesgrasslandcroplandartificial surfaceswater
December weather nearby: Back Mountain 53 mi · State College 55 mi · Hazleton 57 mi · Wilkes-Barre 58 mi · Elmira 60 mi · Harrisburg 67 mi · Lebanon 70 mi · Scranton 70 mi

United States travel facts

Power plugs
Type A / B
120 V · 60 Hz
Prices
≈ 100% of US
price level, 2025
GDP per capita
$90,027
2025
Happiness
6.8 / 10
World Happiness, 2025
Safe drinking water
98%
of population, 2024
Homicide rate
5.8
per 100k, 2023
Road deaths
12.7
per 100k/yr, 2019
Income group
High
World Bank
Religion
Protestant 47%unaffiliated 23%Roman Catholic 21%Jewish 2%

Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.

Data sources

Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Williamsport (41.2412°, -77.0011°, elevation 518 ft), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Monthly air-quality (PM2.5) seasonality is from the CAMS EAC4 reanalysis (Copernicus Atmosphere Monitoring Service), scaled to the WHO annual mean where available. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).